Imaging apparatus

ABSTRACT

The lens arrangement has at least two lenses, wherein a first lens may be used for autofocus and optical image stabilization. The first lens is tilted to compensate for the shaking movement of the hand-held device and to stabilize the image to be captured on the image plane. The tilt action may occur in two degrees of freedom, wherein an actuator causes the first lens to tilt around a pivot. A second lens is a field flattener lens that compensates for the error caused by the difference between the image plane and the focus plane. The field flattener lens causes the focal plane of the first lens to lie in the image plane when the first lens is in a tilted position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 15/727,552, entitled “IMAGING APPARATUS,” filedOct. 6, 2017, which is a continuation of and claims priority to U.S.application Ser. No. 14/606,565, entitled “IMAGING APPARATUS,” filedJan. 27, 2015, which are incorporated herein in their entirety.

BACKGROUND

Digital cameras usually comprise a lens and a sensor for capturing animage by capturing light and converting it into electrical signals.Mobile electronic devices such as smart phones are usually equipped withan imaging apparatus, a camera. The imaging quality of the hand-helddevices may be improved by optical image stabilization. A camera lensusually provides sharp focus on only a single plane. When the lens planeis tilted relative to the image plane, the focus plane is at an angle tothe image plane, causing blurring near the edges of the image capturedfrom the image plane.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

The lens arrangement has at least two lenses, wherein a first lens maybe used for autofocus and optical image stabilization. The first lens istilted to compensate for the shaking movement of the hand-held deviceand to stabilize the image to be captured on the image plane. The tiltaction may occur in two degrees of freedom, wherein an actuator causesthe first lens to tilt around a pivot. A second lens is a fieldflattener lens that compensates for the error caused by the differencebetween the image plane and the focus plane. The field flattener lenscauses the focal plane of the first lens to lie in the image plane whenthe first lens is in a tilted position.

Many of the attendant features will be more readily appreciated as theybecome better understood by reference to the following detaileddescription considered in connection with the accompanying drawings. Theembodiments described below are not limited to implementations whichsolve any or all of the disadvantages of known imaging apparatusesintegrated in hand-held devices.

DESCRIPTION OF THE DRAWINGS

The present description will be better understood from the followingdetailed description read in light of the accompanying drawings,wherein:

FIG. 1 is a schematic diagram of one example of an electronic deviceincorporating an imaging apparatus;

FIG. 2 is a schematic diagram of one example of an imaging apparatushaving a first lens arranged on an optical axis;

FIG. 3 is a schematic diagram of one example of an imaging apparatushaving a first lens and a second lens arranged on an optical axis;

FIG. 4 is a schematic diagram illustrating the effect of a prism intilted position;

FIG. 5a illustrates an exemplary scenario of tilt-enabled optical imagestabilization with two lens groups;

FIG. 5b illustrates an exemplary scenario of tilt-enabled optical imagestabilization with two lens groups;

FIG. 5c illustrates an exemplary scenario of tilt-enabled optical imagestabilization with two lens groups;

FIG. 5d illustrates an exemplary scenario of tilt-enabled optical imagestabilization with two lens groups;

FIG. 5e illustrates an exemplary scenario of tilt-enabled optical imagestabilization with two lens groups; and

FIG. 5f illustrates an exemplary scenario of tilt-enabled optical imagestabilization with two lens groups.

Like reference numerals are used to designate like parts in theaccompanying drawings.

DETAILED DESCRIPTION

The detailed description provided below in connection with the appendeddrawings is intended as a description of the present examples and is notintended to represent the only forms in which the present example may beconstructed or utilized. However, the same or equivalent functions andsequences may be accomplished by different examples.

Although the present examples are described and illustrated herein asbeing implemented in a smartphone, the device described is provided asan example and not a limitation. As those skilled in the art willappreciate, the present examples are suitable for application in avariety of different types of mobile and/or hand-held apparatuses, e.g.in tablets, laptops or gaming consoles.

FIG. 1 shows one example of an electronic device incorporating animaging apparatus, wherein one embodiment of the electronic device is asmartphone. The electronic device comprises a body 100 comprising adisplay 110, a speaker 120, a microphone 130 and keys 140. Theelectronic device comprises an imaging apparatus 150, a camera on onesurface. The electronic device may comprise two or more cameras, forexample one on the front surface 150 and one on the rear surface 160.Cameras may be different; some cameras may be equipped with opticalimage stabilization, whereas some cameras may lack certain features.

FIG. 2 shows one example of an imaging apparatus 210 having a first lens211 arranged on an optical axis. The optical axis is a line along whichthere is some degree of rotational symmetry in an optical system. Theoptical axis is an imaginary line that defines the path along whichlight propagates through the system. The first lens 211 is arranged in alens barrel 220 as a part of a first lens group 212. The first lensgroup 212 inside the lens barrel 220 may operate an autofocus function,a zoom and the optical image stabilization. The optical imagestabilization is achieved by tilting the lens barrel 220 in thedirection that reduces the effect of detected shaking The lens barrel220 is attached to an actuator 221 that tilts the lens barrel. An imageplane 230 is arranged on the optical axis to receive the image from thelens barrel 220. A focal plane 240 is the plane where object appears infocus. The tilted lens barrel 220 causes the focal plane 240 to tilt aswell, wherein the focal plane 240 and the image plane are not aligned.The image plane 230 comprises for example a plurality of light sensingelements that measure the light captured by the light sensing elementsto form an image of pixels. The focal plane projection error 241increases towards the edges of the image plane and the edges of theimage captured on the image plane 230 may be blurred.

FIG. 3 discloses another example of an imaging apparatus. The first lens311 is arranged on the lens barrel 320, wherein the cylindrical shape ofthe wall defines the cylindrical shape of the lens barrel 320. The firstlens may also be arranged in other forms than the lens barrel 320. Thefirst lens 311 may be part of a first lens group 312 arranged in thelens barrel, wherein all the lenses of the first lens group 312 tiltalong with the lens barrel 320. In this example the autofocus or zoomfunction is achieved with the first lens group 312 in the lens barrel320. An actuator 321 is attached to the first lens 311 or the lensbarrel 320. The actuator 321 is configured to tilt the first lens 311 orthe lens barrel. The lens barrel 320 may comprise one or more lenses toform a lens system. The actuator 321 receives information from theoptical image stabilization element 322 that may comprise one or moreorientation sensors such as gyroscope sensors, and the information isused as an input to counter the hand shaking A computing based imagedetection system comparing at least two received images may be used todetect shaking movement in the imaging apparatus. The lens barrel 320 orthe first lens 311 may be tilted to the direction opposite to thedetected movement to counter the shaking—as an example, a correspondingstabilizing function appears in a human eye being focused to a singlepoint that opposes the movement of the head. The optical imagestabilization element 322 may be configured as a separate element 322comprising a computing based device or at least portion of the functionsmay be embedded to the actuator 321. The optical image stabilizationelement 322 is connected to the actuator 321, wherein an electric signalmay travel between the image stabilization element 322 and the actuator321. The actuator 321 causes the first lens 311 to tilt in response tothe optical image stabilization element 322. An image plane 330 isarranged on the optical axis for capturing the image for example with animage sensor. The image plane 330 comprises for example a plurality oflight sensing elements that measure the light captured by the lightsensing elements to form an image of pixels. Examples of the image planecomprise image sensor element, a device that converts an optical imageinto an electronic signal or an image capturing device. A second lens350 is positioned on the optical axis between the first lens 311 and theimage plane 330. The second lens comprises a field flattener lens 351.

In one embodiment the imaging apparatus comprises a first lens 311 on anoptical axis; an actuator 321 coupled to the first lens 311, configuredto cause the first lens 311 to tilt in response to an optical imagestabilization element 322; an image plane 330 on the optical axis; and asecond lens 350 comprising a field flattener lens 351, on the opticalaxis between the first lens 311 and the image plane 330. In oneembodiment the second lens 350 comprises an infrared filter 352. Theinfrared filter reduces the color shading. A further effect of thereduced color shading is a less distorted image. The second lens 350 maybe a concave lens, a double concave lens and/or it may comprise a prismstructure.

In one embodiment the second lens 350 is immovably connected to theimaging apparatus. The field flattener lens 351 does not tilt with thefirst lens 311 or with the first lens group 312; it is arranged toflatten the focal plane to the image plane 330 at all predefined tiltangles of the first lens 311 or the lens barrel 320. The effect isachieved by designing the flattener lens rather than moving the imageplane, image sensor or by moving another element to counteract thetilted first lens 311 or the first lens group 312. In one embodiment thesecond lens 320 is configured to cause the focal point of the first lens311 or the first lens group 312 to lie in the image plane when the firstlens 311 or the first lens group 312 is in a tilted position. The fieldflattener lens flattens the field curvature of the first lens group 312,wherein the curve is defined by series of points caused by varyingtilting angle. The shape of the field flattener lens 351 may becalculated or by selecting an appropriate field flattener lens fromseveral alternatives that allows flattening of the focal point or thefocal plane to the image plane when the first lens 311 or the first lensgroup is in the tilted position. In one embodiment the appropriateflattening lens 351 is selected with the trial and error method.

One embodiment comprises a point around which the first lens 311 istilted, and the series of focal points of the first lens 311 correspondto a focal curve according to the tilting angle, wherein the second lens350 flattens the focal curve to the image plane 330. One embodimentcomprises the actuator 321 configured to allow tilting of the first lens311 around a pivot, and the series of focal points of the first lens 311correspond to a focal curve according to the tilting angle around thepivot, wherein the second lens 350 flattens the focal curve to the imageplane. The point around which the first lens 311 tilts may be virtual orreference information for the imaging apparatus, as the actuator 321 maytilt the first lens 311 or the lens barrel 320 suspending it from sidewalls. Said point may be located on the optical axis. The suspended lensbarrel 320 may be tilted around the point, wherein the actuator 321defines the point around which the first lens 311 is tilted. Without theflattening lens 351 the series of focal points of the first lens 311 orthe first lens group 312 form an arc of a fixed radius, wherein thepoint around which the first lens 311 is tilted forms a center point.The center point may be called the pivot. The pivot is used to arrangethe autofocus and zoom with the first lens group 312 in the lens barrel320. The pivot of the lens barrel 320 may be used as a fixed reference,wherein the autofocus of the lens barrel 320 is used to move the firstlens group 312 further or closer to the image plane 330. In anembodiment the point around which the first lens 311 is tilted may betracked by the actuator 321 and the lens barrel 320, wherein theactuator 321 moves lens barrel 320 along the optical axis and the lensbarrel moves the lenses configured in the lens barrel 320. In anembodiment the first activator for the lens barrel 320 movement is theoptical image stabilization and the second activator is the autofocus.The optical image stabilization element 322 may cause the activation andsend the signal to control the movement. As the autofocus may displacethe pivot, the first lens group 312 is moved accordingly in relation tothe pivot to compensate difference between the pivot and the autofocus.The imaging device is provided with a computing-based device to correctthe pivot after the autofocus function.

In one embodiment the first lens 311 is arranged in a lens barrel 320.In one embodiment the second lens 350 comprises a single lens 351. Inone embodiment the field flattener lens 351 comprises a prism 420 nearthe edges to compensate for the aberration caused by the tilted angletowards the second lens 350. As seen from FIG. 4, the shape of the firstlens 311 is tilted and the light rays travel to a different distancethrough the field flattener lens 351. As an example, without the prism420 the left light ray 410, dashed line, travels on a path 411, solidline, in the field flattener lens 351. The right light ray 412, dashedline, travels a substantially longer distance on a path 413, solid line,through the field flattener lens 351 and moves the light ray 413 furtherto the right 414, solid line, causing aberration to the image as thefocus point 415 is below the image plane. Without the prism 420, thiswould cause the focal plane and the image plane to separate whenapplying the extreme tilt angles. According to the embodiment the prism420 arranged to the field flattener lens 351 causes the distancestraveled by the light rays in the field flattener lens 351 to be evenedout during the extreme tilt angles, as illustrated by the dashed linewith the focal point on the image plane. A Petzval field curvaturedescribes the optical aberration in which a flat object cannot bebrought into focus on a flat image plane. In one embodiment the firstlens 311 is configured to flatten the Petzval field curvature to theimage plane and the second lens 350 is configured to flatten to theimage plane 330 the curvature caused by the tilted first lens 311. Inone embodiment the first lens 311 and the second lens 350 are configuredto flatten the Petzval field curvature to the image plane 330. In oneembodiment the second lens 350 is arranged to flatten the Petzval fieldcurvature to the image plane 351.

FIGS. 5a-5f illustrate exemplary scenarios of tilt-enabled optical imagestabilization with two lens groups. Light rays are illustrated as dashedlines and the diffraction points are illustrated at lens edges. FIG. 5ashows a case, where the first lens group is not tilted and the movablefirst lens group is focused to infinity The focal plane is equivalent tothe image plane Similarly in the case of FIG. 5b the first lens group isnot tilted. The first lens group is focused to macro and the focal planematches the image plane. FIG. 5c shows the first lens group tilted tothe left when focused to macro and the optical image stabilizer isactivated. The second lens corrects the image alignment to the imageplane, maintaining focus by significantly reducing blurring. FIG. 5dshows the first lens group tilted to the right when focused to macro andthe optical image stabilizer is activated. As in the previous example,the second lens corrects the image alignment to the image plane,maintaining focus by significantly reducing blurring. FIG. 5e shows thefirst lens group tilted to the right, focused at infinity and theoptical image stabilization activated. The second lens corrects theimage alignment to the image plane, maintaining focus by significantlyreducing blurring. FIG. 5f shows the first lens group tilted to theleft, focused at infinity and the optical image stabilization activated.The second lens corrects the image alignment to the image plane,maintaining focus by significantly reducing blurring. The optical imagestabilization is used more effectively when focused to infinity, in oneembodiment the optical image stabilization is disabled for the macroimaging.

One embodiment discloses an electronic device incorporating an imagingapparatus, the imaging apparatus comprising a first lens on an opticalaxis; an actuator coupled to the first lens, configured to cause thefirst lens to tilt in response to an optical image stabilizationelement; an image plane on the optical axis; and a second lenscomprising a field flattener lens on the optical axis between the firstlens and the image plane. In an embodiment of the electronic device thesecond lens is immovably connected to the imaging apparatus. In anembodiment of the electronic device the second lens is configured tocause the focal point of the first lens to lie in the image plane whenthe first lens is in a tilted position. In an embodiment of theelectronic device the actuator is configured to allow tilting of thefirst lens around a pivot, and the series of focal points of the firstlens correspond to a focal curve according to the tilting angle aroundthe pivot, wherein the second lens flattens the focal curve to the imageplane. In an embodiment of the electronic device the first lens is in alens barrel. In an embodiment of the electronic device the second lenscomprises a single lens. In an embodiment of the electronic device thesecond lens comprises an infrared filter.

One embodiment discloses a system, comprising an imaging apparatus; anoptical image stabilization element; a processor and a memory storinginstructions that, when executed, control the operation of the opticalimage stabilization element; a first lens on an optical axis; anactuator coupled to the first lens, configured to cause the first lensto tilt for at least two degrees of freedom, in response to a signalreceived from the optical image stabilization element; an image plane onthe optical axis; and a second lens on the optical axis between thefirst lens and the image plane, wherein the second lens is configured tocause the focal point of the first lens to lie in the image plane whenthe first lens is in a tilted position. In an embodiment of the systemthe second lens is immovably connected to the imaging apparatus. In anembodiment of the system the actuator is configured to allow tilting ofthe first lens around a pivot, and the series of focal points of thefirst lens correspond to a focal curve according to the tilting anglearound the pivot, wherein the second lens flattens the focal curve tothe image plane. In an embodiment of the system the first lens is in alens barrel. In an embodiment of the system the second lens comprises asingle lens. In an embodiment of the system the second lens comprises aninfrared filter.

One embodiment discloses an optical image stabilizer for an imagingapparatus, the imaging apparatus comprising a first lens, a lens barreland an image plane. The optical image stabilizer comprises a shakedetector element and an actuator that causes the lens barrel to tilt inresponse to a shake detected by the shake detector element; and a secondlens comprising a field flattener lens, arranged on the optical axisbetween the first lens and the image plane. The field flattener lensflattens the focal plane of the tilted first lens to the image plane.

One embodiment discloses a method, comprising performing optical imagestabilization by tilting a first lens or a first lens group, andarranging a second lens comprising a field flattener lens on the opticalaxis between the lens barrel and the focal plane, wherein the fieldflattener lens reduces the focus error caused by the tilted lens barrel.One embodiment discloses a method for optical image stabilization on animaging apparatus, comprising a first lens or a first lens grouparranged on an optical axis; an actuator coupled to the first lens orthe first lens group, causing the first lens or the first lens group totilt in response to an optical image stabilization element; an imageplane arranged on the optical axis; and a second lens comprising a fieldflattener lens, arranged on the optical axis between the first lens orthe first lens group and the image plane. One embodiment discloses amethod for optical image stabilization on an imaging apparatus,comprising a first lens or a first lens group arranged on an opticalaxis; means for tilting the first lens or the first lens group inresponse to an optical image stabilization information; an image planearranged on the optical axis; and a second lens comprising a fieldflattener lens, arranged on the optical axis between the first lens orthe first lens group and the image plane.

The tilt-enabled optical image stabilization allows for the imagingapparatus several degrees of shake that can still be corrected. Thefunctionality can be used to improve panorama imaging, where the cameratakes several images and combines them into one single wide image.Tilt-enabled optical image stabilization may be used even in macroimaging, where most image stabilizing techniques are ineffective. In anembodiment the extreme tilt angles are 3 degrees from the centerposition; in another embodiment the extreme tilt angles are 1.5 degreesfrom the center position.

Alternatively, or in addition, the functionality described herein can beperformed, at least in part, by one or more hardware components orhardware logic components. For example, and without limitation,illustrative types of hardware logic components that can be used includeField-programmable Gate Arrays (FPGAs), Program-specific IntegratedCircuits (ASICs), Program-specific Standard Products (ASSPs),System-on-a-chip systems (SOCs), Complex Programmable Logic Devices(CPLDs), Graphics Processing Units (GPUs). For example, some or all ofthe optical image stabilization element functionality may be performedby one or more hardware logic components.

An example of the apparatus or a system described hereinbefore is acomputing-based device comprising one or more processors which may bemicroprocessors, controllers or any other suitable type of processorsfor processing computer executable instructions to control the operationof the device in order to control one or more sensors, receive sensordata and use the sensor data. Platform software comprising an operatingsystem or any other suitable platform software may be provided at thecomputing-based device to enable application software to be executed onthe device.

The computer executable instructions may be provided using anycomputer-readable media that is accessible by computing based device.Computer-readable media may include, for example, computer storage mediasuch as memory and communications media. Computer storage media, such asmemory, includes volatile and non-volatile, removable and non-removablemedia implemented in any method or technology for storage of informationsuch as computer readable instructions, data structures, program modulesor other data. Computer storage media includes, but is not limited to,RAM, ROM, EPROM, EEPROM, flash memory or other memory technology,CD-ROM, digital versatile disks (DVD) or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other non-transmission medium that can be usedto store information for access by a computing device. In contrast,communication media may embody computer readable instructions, datastructures, program modules, or other data in a modulated data signal,such as a carrier wave, or other transport mechanism. As defined herein,computer storage media does not include communication media. Therefore,a computer storage medium should not be interpreted to be a propagatingsignal per se. Propagated signals may be present in a computer storagemedia, but propagated signals per se are not examples of computerstorage media. Although the computer storage media is shown within thecomputing-based device it will be appreciated that the storage may bedistributed or located remotely and accessed via a network or othercommunication link, for example by using communication interface.

The computing-based device may comprise an input/output controllerarranged to output display information to a display device which may beseparate from or integral to the computing-based device. The displayinformation may provide a graphical user interface, for example, todisplay hand gestures tracked by the device using the sensor input orfor other display purposes. The input/output controller is also arrangedto receive and process input from one or more devices, such as a userinput device (e.g. a mouse, keyboard, camera, microphone or othersensor). In some examples the user input device may detect voice input,user gestures or other user actions and may provide a natural userinterface (NUI). This user input may be used to configure the device fora particular user such as by receiving information about bone lengths ofthe user. In an embodiment the display device may also act as the userinput device if it is a touch sensitive display device. The input/outputcontroller may also output data to devices other than the displaydevice, e.g. a locally connected printing device.

The term ‘computer’ or ‘computing-based device’ is used herein to referto any device with processing capability such that it can executeinstructions. Those skilled in the art will realize that such processingcapabilities are incorporated into many different devices and thereforethe terms ‘computer’ and ‘computing-based device’ each include PCs,servers, mobile telephones (including smart phones), tablet computers,set-top boxes, media players, games consoles, personal digitalassistants and many other devices.

The methods described herein may be performed by software in machinereadable form on a tangible storage medium e.g. in the form of acomputer program comprising computer program code means adapted toperform all the steps of any of the methods described herein when theprogram is run on a computer and where the computer program may beembodied on a computer readable medium. Examples of tangible storagemedia include computer storage devices comprising computer-readablemedia such as disks, thumb drives, memory etc. and do not only includepropagated signals. Propagated signals may be present in a tangiblestorage media, but propagated signals per se are not examples oftangible storage media. The software can be suitable for execution on aparallel processor or a serial processor such that the method steps maybe carried out in any suitable order, or simultaneously.

This acknowledges that software can be a valuable, separately tradablecommodity. It is intended to encompass software, which runs on orcontrols “dumb” or standard hardware, to carry out the desiredfunctions. It is also intended to encompass software which “describes”or defines the configuration of hardware, such as HDL (hardwaredescription language) software, as is used for designing silicon chips,or for configuring universal programmable chips, to carry out desiredfunctions.

Those skilled in the art will realize that storage devices utilized tostore program instructions can be distributed across a network. Forexample, a remote computer may store an example of the process describedas software. A local or terminal computer may access the remote computerand download a part or all of the software to run the program.Alternatively, the local computer may download pieces of the software asneeded, or execute some software instructions at the local terminal andsome at the remote computer (or computer network). Alternatively, or inaddition, the functionally described herein can be performed, at leastin part, by one or more hardware logic components. For example, andwithout limitation, illustrative types of hardware logic components thatcan be used include Field-programmable Gate Arrays (FPGAs),Application-specific Integrated Circuits (ASICs), Application-specificStandard Products (ASSPs), System-on-a-chip systems (SOCs), ComplexProgrammable Logic Devices (CPLDs), etc.

Any range or device value given herein may be extended or alteredwithout losing the effect sought.

Although the subject matter has been described in language specific tostructural features and/or acts, it is to be understood that the subjectmatter defined in the appended claims is not necessarily limited to thespecific features or acts described above. Rather, the specific featuresand acts described above are disclosed as examples of implementing theclaims and other equivalent features and acts are intended to be withinthe scope of the claims.

It will be understood that the benefits and advantages described abovemay relate to one embodiment or may relate to several embodiments. Theembodiments are not limited to those that solve any or all of the statedproblems or those that have any or all of the stated benefits andadvantages. It will further be understood that reference to ‘an’ itemrefers to one or more of those items.

The steps of the methods described herein may be carried out in anysuitable order, or simultaneously where appropriate. Additionally,individual blocks may be deleted from any of the methods withoutdeparting from the spirit and scope of the subject matter describedherein. Aspects of any of the examples described above may be combinedwith aspects of any of the other examples described to form furtherexamples without losing the effect sought.

The term ‘comprising’ is used herein to mean including the method blocksor elements identified, but that such blocks or elements do not comprisean exclusive list and a method or apparatus may contain additionalblocks or elements.

It will be understood that the above description is given by way ofexample only and that various modifications may be made by those skilledin the art. The above specification, examples and data provide acomplete description of the structure and use of exemplary embodiments.Although various embodiments have been described above with a certaindegree of particularity, or with reference to one or more individualembodiments, those skilled in the art could make numerous alterations tothe disclosed embodiments without departing from the spirit or scope ofthis specification.

1. A method performed on an imaging apparatus comprising an image plane,a first lens and a second lens, the second lens comprising a fieldflattener, the image plane, the first lens, and the field flattener onan optical axis, the field flattener being between the first lens andthe image plane, the method comprising: causing, via an actuator coupledto the first lens, the first lens to tilt in one of a plurality ofpredefined tilt angles in response to an optical image stabilizationelement; and causing the field flattener lens to flatten a focal planeto the image plane at each of the plurality of predefined tilt angles.